What is complexity of this code And Explain How Plzzzz

1 
public class PrimeFactorsEffective {
    public static List<Integer> primeFactors(int numbers) {
        int n = numbers;
        List<Integer> factors = new ArrayList<Integer>();
        for (int i = 2; i <= n / i; i++) {
            while (n % i == 0) {
                factors.add(i);
                n /= i;
            }
        }
        if (n > 1) {
            factors.add(n);
        }
        return factors;
    }



Can Any one suggest me the most optimised code of prime factorisation which is used by most competitive programmer.
2

Time complexity is \mathcal{O}(\sqrt N) as you iterate until the following conditions is violated

i \le\frac{N}{i} \equiv i^2 \le N \equiv i \le \sqrt N
3

thanks